The overall goal of our project is to pilot and validate the use of computerized clinical vignettes as a tool to evaluate the quality of care in publicly-funded HIV/AIDS clinics in Mexico, which, like several other middle-income countries, has recently guaranteed access to antiretroviral therapy but recognizes considerable variability in practice patters by HIV physicians. Our interest in the use of clinical vignettes stems from their recent validation by Peabody et al in the United States as a sensitive, robust tool to measure quality of physician care in a variety of practice settings and at various levels of training. The three specific aims of our project are: (1) To develop, for four clinical scenarios with which an HIV-infected patient might present, a set of ideal practice criteria to serve as measurement standards. These will be adapted from the most recent official Mexican HIV/AIDS Clinical Guidelines. (2) To develop three methodologically distinct tools with which to determine how well physicians score against the ideal practice criteria developed in aim (1). These tools will consist of (a) a team of eight standardized patients trained to simulate the four clinical scenarios developed in aim (1) and to evaluate physicians using a visit report form;(b) a set of four on-line clinical vignettes adapted for the Mexican context from those already developed by our group at UCSF;and (c) a team of chart reviewers, armed with a data abstraction form to be used in retrospective chart review of visits conducted by the standardized patients. (3) To conduct a validation study of clinical vignettes as a tool to measure quality of HIV care in 12 publicly funded clinics in Mexico City, and the states of Mexico, Baja California de Norte, and Veracruz. This study will consist of a cross-sectional comparison of the quality scores generated by a sample of HIV physicians in response to the three measurement tools developed in aim (2). We plan a 24-month project, consisting of nine months to develop instruments and train study personnel, followed by nine months of data collection and six months of data analysis, results of which will be used to plan a more comprehensive study of HIV care country-wide. High Quality care for HIV infection requires access to both medications and skilled clinicians. Developing tools to measure quality of HIV care by physicians is an essential component to scaling up access to antiretroviral therapy in middle-income countries such as Mexico.